In this research attention will be paid to the neural mechanism by which spatial resolution is accomplished in the human observer. Several tests have shown that performance in certain resolution tasks is better than can be predicted from the known capabilities of the optics of the eye and the retinal mosaic. Hence a neural processing mechanism must be at play which allows precise identification of small spatial differences at the expense of some of the other dimensions, perhaps time and absolute localization. Experiments will be carried out on human observers to delineate their resolution capabilities with exposure duration, luminance, adaptation, binocularity and spatial features as parameters. Attempts will be made to identify test variables that allow the clinician to distinguish between various modes by which disease processes interfere with normal neural mechanism of resolution and that will aid in the alleviation of resolution decrements by optical and other means.